DNA Replication and Repair

First, the two strands of DNA unwind and expose their bases. Then unattached nucleotides pair with exposed bases. Thus, replication results in DNA molecules that consist of one "old" strand and one "new" strand (semiconservative).

Unwinding requires many kinds of enzymes. DNA polymerases assemble the nucleotides into nucleic acids. Strands can only be assembled in the 5' to 3' direction.

Mistakes can occur during replication. DNA polymerase can read correct sequences from the complementary strand and, together with DNA ligase, can repair mistakes in an incorrect strand.

DNA polymerases, DNA ligases, and other enzymes engage in DNA repair when they "read" the complementary sequence on the other strand and restore it. These same enzymes are responsible for the breaking and reattaching of DNA strands that occurs in crossing over.

The DNA replication tutorial (Audio - Important) has some really great animations and explanations of this process.

These animations(Audio - Important) describe DNA replication:
DNA replication1,
DNA replication 2.

REVIEW: A DNA strand having the sequence C-G-A-T-T-G would be complementary to the sequence

REVIEW: One species' DNA differs from others in its _____.

REVIEW: When DNA replication begins, _____.

REVIEW: DNA replication requires
a. free nucleotides
b. new hydrogen bonds
c. many enzymes
d. all of the above

REVIEW: Replication of DNA

REVIEW: The DNA molecule is usually made up of how many strands?

REVIEW: The appropriate adjective to describe DNA replication is

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